Ear Infection (otitis externa)

Otitis externa (commonly known as an ear infection) is an inflammation or infection of the external ear canal. Bacteria, yeast, ear mites, allergies and hormone imbalances can all cause otitis externa. Once an ear infection starts you may see your pet scratching at their ears, shaking their head or holding one ear slightly dropped. Discharge and odour may be noticeable as well.


Causes of Ear Infections


Yeast infection
A yeast infection is caused by an overgrowth of yeast, which is a fungus. A yeast called Malassezia pachydermatis lives in most ear canals and on most skin. In normal numbers it causes no problems; however, if the secretions in its environment favor its growth it will proliferate. In large numbers, Malassezia produces itching and irritation. Yeast infection with Malassezia is the most common type of ear infection in dogs and is frequently accompanied by bacterial infection. As with other types of infection, cleaning and topical medication are important parts of management. Often some kind of cortisone-derivative is prescribed to help with the inflammation and wax production in the ear canal to create an ear environment less conducive to yeast growth.

Bacterial infection
Pseudomonas is a common bacteria strain that causes ear infections. This bacteria is particularly resistant and able to become more resistant if treatment is not effective from the beginning. Therefore if a bacterial infection is suspected,  a culture and sensitivity test may be recommended before treatment with an antibiotic is started. This will allow us to pinpoint an exact antibiotic that the bacteria is sensitive to in order to treat the infection effectively.

For persistent, chronic bacterial ear infections oral antibiotics maybe combined with a topical antibiotics to treat the infection systemically and at the site of infection.

Ear mites

ear mite (2)Ear mites usually are a problem seen in cats. They are tiny infectious organisms that can cause infection in your pet’s ears. Infection usually produces a characteristic dry black ear discharge that looks like coffee grounds. The mites are seen by examination of a sample of this discharge under a microscope. The discharge is composed of ear wax, blood, inflammatory biochemicals, and the ear mites themselves.

One particular symptom of an allergy in your pet may be chronic or recurrent ear infections, particularly yeast infections. These infections respond to antifungals and antibiotics but reoccur after the medications are discontinued. If an allergy is suspected, allergy testing or an elimination diet trial may be recommended.

Hormone Imbalances
Hormone imbalances or abnormalities, (for example, hypothyroidism in dogs) can also lead to ear infections. When there is a hormone imbalance, your pet’s immune system may be weakened. Thus making them more prone to ear infections. Diagnostic blood screening can help the veterinarian determine if your pet has a metabolic disease and proper treatment can be started.

Complications of Ear Infections
If the infection reaches the middle ear, affected animals may have a head tilt, a lack of balance, and unusual back-and-forth eye movements called nystagmus. These symptoms are called vestibular signs and represent a complication of middle ear infection. Middle ear infections can also cause paralysis of the facial nerve, leading to a slack-jawed appearance on that side of the face.

Treating Ear Infections
Most ear infections are cleared up with an ear cleaning at the veterinary clinic, followed by medication at home. If there is only mild debris in the ear canals, a simple cleaning of the ear may be enough; however, in many cases, a full ear flush is needed to even examine the eardrum. A sample of ear discharge is usually examined under the microscope (looking for bacteria, yeast and/or ear mites) to assist in selecting medications for home use. After a couple of weeks of home treatment, the ear canals are rechecked to be sure the infection is gone. In most cases this completes treatment but for stubborn cases, more work up may be needed.


Some dogs have chronic ear problems in which the infection is not controlled by topical medications or returns when the medication is discontinued. In these cases, the ear discharge should be cultured so that the precise bacteria can be pinpointed and treated specifically. Regular treatment at home with disinfecting ear washes should become part of the pet’s grooming routine.


Further testing may be in order to determine why the infection continues to recur. Allergy is the most common reason for recurrent ear problems but hormone imbalances can also be underlying causes.

If the infection can’t be cleared with medications and there are no other underlying abnormalities, the vertical ear canal may need to be opened surgically. This enables debris to be removed more effectively.

If the canal becomes so scarred (from repetitive topical medications applications and ear cleanings) that it is practically closed, ablation may be the final option. In this surgical procedure, the entire ear canal is removed and healthy tissue is allowed to grow in. These procedures are last resorts after severe infection has made effective medical treatment impossible. Although surgery is expensive, dogs with chronic severe otitis usually require no further ear treatment for the rest of their lives.

Administering Ear Medication

  1. Have the medication ready and the cap off.
  2. For dogs, hold their head still with one hand. Try wrapping your arm around their neck like a hug and use your hand to hold the head still. Then the other hand is used to administer the medication. Many people hold the tip of the affected ear to help hold the dog still. Be very careful to not hold the ear too firmly. Be prepared for your dog to flinch once the medication touches the ear. For cats, wrapping them in a towel like a “kitty burrito” with their head out will make it easier to administer the ear medication. Now you can hold the body of your cat tucked between your arm and body and use one hand to hold the head and the other to administer the medication.
    Wrapping a "kitty burrito" can help restrain your cat when cleaning the ears.

    Wrapping a “kitty burrito” can help restrain your cat when cleaning the ears.

  3. Place the medication dropper just inside the opening to the ear. Do not push the tip into the canal.
  4. Administer the prescribed amount of medication into the ear opening.
  5. Remove the dropper from the ear opening and gently rub the base of the ear to distribute the medication deeper inside the ear.

Cleaning Your Pet’s Ears

  1. Make sure your pet is properly restrained. Giving your dog a “hug” to restrain their head, or using the “kitty burrito” technique for cats.
  2. The first thing to do is use a gauze or Kleenex to wipe away discharge that is on the surface.
  3. Gently pull up on the ear and partially fill the ear with the cleaning solution. By straightening out the ear you allow the cleaning solution to flow down the ear canal to where the infection and debris are located.
  4. After the canal had been partially filled massage the base of the ear canal very gently. Most pets find this part soothing.
  5. Let your pet shake its head if it wants to. Then use a gauze or Kleenex to soak up the fluid that comes out of the ear.


Tips for Treating Your Pets’ Ears


  • As a general rule you should clean the ears by letting the cleaning solution flush up, bringing the debris and discharge to the outside of the canal to be wiped away.
  • You should not put Q-tips into your pet’s ears. Q-tips can damage the sensitive tissue that lines the ear canal. Also, an ear drum can easily be ruptured by placing objects in the ear canal, especially if the ear has an infection.
  • If have been instructed to clean and use ear medication for your pet, ensure you do the cleaning first, then apply the medication. This way you won’t wash the medication out of the ear.